1. Field of the Invention
The present invention relates to an eye image pickup apparatus used by an iris authentication system for identifying an individual using iris information of a human being or another animal.
2. Description of the Related Art
The technique disclosed in Japanese Examined Patent Publication No. H05-084166(B2) is well known as an example technique for obtaining the iris image of a human being by a camera and authenticating an individual. Generally, to perform individual authentication, the iris authentication apparatus emits near-infrared light to the eye of a person to be authenticated, photographs the eye image using a single video camera having a telephoto lens, extracts iris information from the obtained eye image, compares the iris information with data already registered to an iris information database.
For the personal authentication, the accuracy for photographing the eye image is the great factor in order to exactly extract the iris information of a person to be authenticated, and his or her eye of a predetermined size must be photographed within a screen. Therefore, the position of the eye is detected from the image of the entire face, and only the eye is zoomed up by a zoom lens to obtain the eye image of a predetermined size.
An iris authentication apparatus of two-camera type, disclosed in Japanese Unexamined Patent Publication No. H10-040386, includes a wide-angle camera for photographing the entire face and a moving telephoto camera for photographing only the eye portion. According to this apparatus, the position of the eye is detected in the image of the face or the upper body obtained by the wide-angle camera, and is transmitted as coordinate data in the wide-angle image to the movement controller of the moving telephoto camera. Based on the positional information, the eye image of a predetermined size is photographed by aiming the moving telephoto camera at the eye of a target person, and detailed iris information is thus obtained.
However, when the iris authentication apparatus is mounted on a terminal device, such as a portable telephone, for which the reduction of the size, the weight and the price is strongly demanded, the following problems have occurred. For an iris authentication apparatus that employs a single camera to zoom up and photograph an iris image, a high-level zooming function must be provided so as to photograph a wide-angle face image and an telephoto eye image, so that the reduction of the size and the price of a lens can not be implemented.
Further, since the iris authentication apparatus of two-camera type must be equipped with two cameras, a wide-angle camera and a telephoto camera having a moving function, the size and the weight of the camera portion can not be reduced. Further, since a driving mechanism and circuit for moving the telephoto camera are also required, it is practically impossible that this iris authentication apparatus is mounted on the portable terminal device.